This invention relates to a combination lock. Particularly, the present invention has a number disc for setting a code of several digits for locking and unlocking.
A small light lock is generally used with a chain for preventing a bicycle or motorcycle from being stolen. Nowadays, combination locks are widely used for this purpose, to avoid embarrassment of losing a key or breaking a key in the key hole, and for convenience of use.
A conventional combination lock, shown in FIG. 11, includes a male member 10, and a female member 20. The male member 10 has a long rod 101 and plurality of teeth 102 formed on the rod 101. The female member 20 has a cylinder 201, and several number discs 202 and spring discs 203 are secured by a C-shaped locking ring 204 positioned in an annular groove 205 of the female member 20. After the number discs 202 and the spring discs 203 are assembled with he female member 20, a central keyway-shaped passageway is formed for the rod 101 with the teeth 102 of the male member 10 to be received therein.
In the case where the conventional combination lock is to be locked, the number discs 202 are rotated to the preset number used to unlock the lock, so that the center passageway is formed in the female member 20 and the male member 10 can extend into the cylinder 201 of the female member 20. After that, the number discs 202 are rotated to any number, except that used for unlocking, to lock the male member in the female member and make it impossible to be pulled out. If the number lock is to be unlocked, the number discs 202 are rotated to the preset number to establish the unlocking position.
However, the conventional combination lock includes many sets of number discs representing a large portion of the cost of the lock, the total cost of the lock thereby being high. In addition, the number discs have a rather large dimension, making the whole lock less handy to use.